There is disclosed in European patent specification No. 89141A of Sept. 21, 1983 a cathode having a nickel or nickel-coated iron substrate and a catalytically active coating containing a powder mixture of an intermetallic AB.sub.5 compound and nickel. The coating was applied from an aqueous polysilicate slurry and sintered in hydrogen to create a metallurgical bond to the substrate. This cathode exhibits excellent electrocatalytic activity. However, the following drawbacks were encountered during manufacture of cathodes of industrial size. First manufacturing costs were high, primarily because of the high temperature, hydrogen atmosphere sintering step. Secondly, the cathode substrate was extremely soft after heat treatment. Finally, the high sintering temperatures and times required to produce a coating with good abrasion resistance had an adverse effect on catalytic activity.
Also in European patent specification No. 89141A, there is disclosed hydrogen evolution cathodes containing polytetrafluoroethylene (PTFE). These PTFE-containing cathodes were fibrillated to produce the PTFE binder matrix. They were highly efficient, but had the following drawbacks:
1. Fibrillation produced some mechanical working and physical damage to the AB.sub.5 catalyst. PA1 2. The fabrication process was not amendable to producing a thin, catalytically active coating on cathode substrates preferred by industry. PA1 3. The polymer content was too low to give sufficient strength, i.e., catalyst was lost in visible quantities during short electrolysis trials. PA1 as A one or more members of the group consisting of rare earth elements and calcium which can be replaced in part, e.g., up to about 0.2 atom by zirconium or thorium or both. PA1 as B nickel and/or cobalt which may be replaced in amounts up to about 1.5 atom by aluminum, copper, tin, iron and/or chromium,
In addition to the aforementioned patent specification there is to be noted the publication "A study of Gas Evolution in Teflon Bonded Porous Electrodes III, Performance of Teflon Bonded Pt Back Electrodes for H.sub.2 Evolution; ACC Tseung et al Electrochemica Acta, 1976 Vol. 21 pp. 315-318. The Tseung et al article deals with cathodes containing at least a troy ounce of platinum per square meter, i.e., cathodes having a material cost of about $400 (U.S.) per square meter of cathode. For practical industrial purposes, such cathodes are too expensive.